The present invention relates to a disc drive storage system. In particular, the present invention relates to an improved head gimbal assembly which reduces gimbal separation from the load arm which may result from operating shock or shocks introduced during shipping and handling.
Disc drives are well known in the industry. Such drives use rigid discs coated with a magnetizable medium for storage of digital information in a plurality of circular, concentric data tracks. The discs are mounted on a spindle motor which causes the discs to spin and the surfaces of the discs to pass under respective hydrodynamic (e.g. air) bearing disc head sliders. The sliders carry transducers which write information to and read information from the disc surfaces.
An actuator mechanism moves the sliders from track to track across the surfaces of the discs under control of electronic circuitry. The actuator mechanism includes a track accessing arm and a suspension for each disc head slider. The suspension includes a load beam and a gimbal spring. The load beam provides a preload force which forces the slider toward the disc surface. The gimbal spring and load beam may be formed of separate members coupled for operation or may be integrally formed.
The slider includes an air bearing surface which faces the disc surface. As the disc rotates, the disc drags air under the slider along the air bearing surfaces in a direction approximately parallel to the tangential velocity of the disc. As the air passes beneath the air bearing surface, skin friction on the air bearing surface causes the air pressure between the disc and the air bearing surface to increase, which creates a hydrodynamic lifting force that causes the slider to lift and fly above the disc surface.
The preload force supplied by the load beam counteracts the hydrodynamic lifting force. The preload force and the hydrodynamic lifting force reach an equilibrium based upon the hydrodynamic properties of the slider and the speed of rotation of the disc. The slider preferably flies with a positive pitch in which the leading edge of the slider (or air bearing surface) flies at a greater distance from the disc surface than the trailing edge. This ensures that the transducer, which is typically carried at the trailing edge, remains close to the disc surface and provides a stable fly height profile across the disc surface.
Typically, the suspension includes a load dimple defining a load and pivot point for the system. The load force is supplied to the slider by the load beam through the load dimple. The load dimple also provides a pivot point for the slider to pitch and roll relative to the disc surface. The slider is supported by the gimbal spring which typically includes struts which cooperatively support the slider for movement relative to the load dimple.
As previously explained, the gimbal spring and load beam may be formed of separate members or integrally formed. The load beam and gimbal spring are flexibly coupled to one another for movement of the gimbal spring relative to the load beam to facilitate the desired fly; and the desired pitch and roll characteristics. During operation or shipping and handling, the gimbal spring may deflect or move relative to the load beam. Movement of the gimbal spring relative to the load beam or arm causes separation of the slider supported by the gimbal spring and load arm, thus affecting the performance characteristics of the head. Thus, it is desirable to design a gimbal spring that facilitates the desired pitch and roll characteristics of a slider supported thereby, while restricting movement of the spring relative to a load arm to reduce separation between the load arm and slider, which may be referred to as dimple separation.